High Nitrates please help

This is a discussion on High Nitrates please help within the Beginner Saltwater Aquariums forums, part of the Saltwater Fish and Coral Reef Tanks category; -->
Hello,
I have a 55 gallon salt water aquarium. The tank was up and established for about 8 years with no major issues to ...

I have a 55 gallon salt water aquarium. The tank was up and established for about 8 years with no major issues to speak of. I had to leave town for around a year due to work and the left the care of my tank to a family member. This is where the fun starts within 3 months the tank crashed. Upon returning home I found the tank to be about 15 gallons low of water with some of the live rock exposed (dead).

The tank has approximately 100lbs of live rock some of which appears to be dead.
Sand bed is about 2 inches and around 8 - 9 years old.

I have done small WCs and attempted to get things back in order for the past two months give or take. I have been dosing frytzyme 460 a normal regimen of Kent Marine additives as well as running carbon and a nitrogen sponge. Which does not appear to bring down the nitrates at all.

So, water changes of 30 gallons have been done daily for two days with zero affect.

The folks at my LFS are recommending that I change out the sand bed and I am considering it but wanted to ask some of the experts here with more experience in this hobby for any advice you may have to identifying the source of the problem.

If its of a smaller grade I would certainly get new substrate.Are the rocks covered in anything that might prevent the osmosis process or the denitrification effects of the rock? Have you tried Purigen?

Visually the LR in the highest elevations of the tank has gone from purple with coralline growth to white. The stuff lower in the tank has gone from purple to pink. But it does not appear to be covered with anything.
Currently my API test kit and LFS tests show water params at NH3 = 0 N02 = 0 N03 = 160 ppm.
I would be seeing NH and NO2 if I had additional die off or something inhibiting the denitrification process right ?
I haven't used purigen.

In a well established aquarium you may very well have enough bacteria present to not show signs of ammonia and nitrites. but the saturation of nitrates will still raise much more rapidly as even if you do have denitrifying bacteria present it does not consume nitrate as fast as most of the aerobic bacteria wich consume the ammonia and nitrite.
I might also recommend the use of a couple types of macro algae ,temporarily,to help remove the nitrate naturally .

Bio-balls can be nitrate factories. Rinse them out well and/or toss them completely. I use chato (spelling?) in my sump and I always have 0 nitrates, even without water changes. I'd get a bunch of that, and toss the bio balls.

For the suggestion to remove bio-balls. Will this not be detrimental to the bacteria population ?

I assume I can replace with liverock rubble and chato (sp) or some macro algae. Is it ok to replace all of the bio-balls at one shot or should it be done gradually ? Also should the live rock rubble be submerged or is it ok to simple allow the trickle of water over the liverock rubble ?

For the suggestion to remove bio-balls. Will this not be detrimental to the bacteria population ?

I assume I can replace with liverock rubble and chato (sp) or some macro algae. Is it ok to replace all of the bio-balls at one shot or should it be done gradually ? Also should the live rock rubble be submerged or is it ok to simple allow the trickle of water over the liverock rubble ?

If you have enough live rock (a lb. or more, per gal of water) all the healthy things you need are there to take care care of nitrates, along with any macro algae. Removing the bio balls won't hurt anything, IMO.

Tell me more about your set up. Do you have some type of hang on back filter that could be the cause with sponges? I don't use any bio balls, but have a lot of live rock, and never do I have nitrates. I also have lots of critters like pods and mysis shrimp in my tank and sump. Obviously some are being eaten by fish in my tank, but every so often I buy a big amount of them on Reefs2go. Do you have snails, crabs etc to eat stuff that reaches your sand bed?

Live rock and live sand are all that is currently in the tank. I pulled all the rock placed in rubber made containers (100lbs). Replaced the sandbed (60 lbs) and did 95% water change. With no rock in the tank for past 24 hours minus a few small pieces (10 lbs) i recently aquired everything is reading zeros as it should be. I am contemplating whether i should place the other 90lbs of rock back in the tank or just go ahead and cook it. I'll probably put it back check the nitrates over the next couple days to understand if the origional live rock is the source. I need to make sure the tank is stable before adding any critters but i do understand the need for a clean up crew etc.